As is well known, a reset signal generation device is widely utilized in various electronic/electrical applications. The conventional reset signal generation device is employed with various electronic equipment, e.g., a microcomputer, in order to allow the microcomputer to effectively carry out a series of processes therein. In general, the microcomputer requires a stable input supply voltage and a correct input clock signal so as to perform all of the processes without incurring errors or malfunction therein.
However, the input supply voltage and/or the input clock signal may be sometimes unstable or incorrect due to, e.g., an instantaneous power failure, an overload at the power supply and the like, resulting in errors or malfunctioning thereof. Consequently, to detect an erroneous input supply voltage and/or input clock signal to the microcomputer and produce a stable reset signal, various reset signal generation devices have been proposed.
One of such devices is disclosed in U.S. Pat. No. 4,434,403, which comprises an error detection circuit and a delay circuit to monitor both the input supply voltage and the input clock pulses and produce a stable reset signal if a low input supply voltage is detected or one of the input clock pulses is missed.
Since, however, the device has to employ various analog circuitries, it is rather difficult to precisely adjust the circuit parameters to obtain a reliable reset signal. Further, it is difficult to alter or update the generation time and the release time of a reset signal as the device comprises the analog circuitries which are intrinsically set by an integrated circuit(IC) to provide a stable reset signal.